IMPROVED RATE FORMULAS FOR DIELECTRONIC RECOMBINATION

Improved rate forumlas for dielectronic recombination (DR) have been obtained by fitting all of the existing DR data for ions with core charges Z(c) less than 50 and the number of electrons N in the target ions less than 13. The fitting procedure used here is distinct from that used in earlier works in that the total rates are divided into five different excitation modes, rather than fitting the rates for each isoelectronic sequence. This method allows better interpolation among the ions for which no explicit data are available and also incorporates detailed information on the contributions from the different shell excitations. Because of gaps in the available data, the formulas obtained here are reliable only for N < 13 and Z(c) < 50. The need for additional benchmark data for ions with 5 < N < 9 and N > 12 is stressed. Our formulas are estimated to be reliable to +/- 50% or better. Sample rates are generated for C, 0, Mg, Ar, Fe, Se, and Mo ions. The rates for other ions can be easily generated and checked by comparison with the values given here.